CZ283915B6 - Process for producing flax yarn by wet spinning - Google Patents

Abstract

According to the invention, the fibres originating from stripping are subjected to the following preliminary operations: a. cutting to a length of between 150 and 400 mm, b. preimpregnation with water, c. action of steam at a pressure of between 10 and 15 bars for a period of between 20 and 60 seconds, d. decompression to atmospheric pressure, e. washing and drying, which are subjected to the preparation stages on any type of material: linen, wool or cotton; the fibre sliver obtained is finally spun wet. The linen yarn obtained has the appearance and the structure of a linen yarn produced by the wet method and has a flexibility which makes it suitable for use in millinery and on a knitting loom.

Description

(57)

In a wet linen yarn manufacturing process, the screed fibers are subjected to various preparatory processes to form a fiber strand, after which the fiber strand or yarn is wet-spun to form a linen yarn. Before the preparatory processes, the screed fibers are cut to a length of between 150 and 400 mm, the cut fibers are soaked with water, the water-soaked fibers are subjected to steam in the reactor under a pressure of 1 to 1.5 MPa for 20 to 60 seconds The reactor outlet port is then opened to cause expansion to atmospheric pressure by rapidly shifting the internal pressure of the reactor to atmospheric pressure, after which the treated fibers are washed and dried. The preparation of the sliver or roving can be carried out on any type of preparation device, namely a device primarily intended for preparing flax, wool or cotton. The flax yarn obtained in this manner has the appearance and structure of the wet spun linen yarn and at the same time has the flexibility making it suitable for use in knitting on a knitting machine.

Processes for producing wet flax yarn

Technical field

BACKGROUND OF THE INVENTION The present invention relates to the spinning of flax, and more particularly to wet spinning of flax, in which a strand or strand of substantially parallelized fibers is immersed in a bath designed to soften sticky acrylics. subsequent stretching (drafting). The invention relates to a method aimed at improving the prior art, in particular by allowing under certain conditions to exclude passage through a flugelhorn, to obtain a wet-spun linen yarn having improved properties, in particular as applicable in knitting on knitting machines. More particularly, it relates to a method for producing a wet linen yarn, in which the screed fibers are subjected to various preparatory processes to form a fiber strand, after which the fiber strand or yarn is wet-spun to form the linen yarn.

BACKGROUND OF THE INVENTION

Wet spinning is well known. It is based on fibers derived from scouring, either from scoured flax in the true sense of the word or from scoured undergrowth flax, or from seed tow, which undergo preparatory processes, such as combing and / or carding, sowing and drawing, to form a sliver, that is, a strand that is fine and regular, of substantially parallelized fibers, followed by spinning by a flugelhorn, where the stranded strand is transformed into a strand formed by a slightly twisted strand and then by a spinning machine for wet spinning.

The yarn obtained by wet spinning technology has a natural appearance and a specific texture to be seen, which results from the presence of residual organic sticky substances and from the method of breaking and sliding the elementary fibers against each other during the drawing process. However, the presence of organic sticky substances (pectins, hemicellulose, lignin ...), which allows the yarn to be better cohesive, is characterized by a considerable disadvantage in terms of increasing its stiffness. Thus, the wet-spun linen yarn obtained in the traditional manner does not have sufficient flexibility for use in knitting, knitting machines, which greatly limits its industrial sales.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a process for producing linen yarn by wet spinning, which overcomes the above-mentioned disadvantages while retaining the appearance and structure of the wet knitted yarn while having sufficient flexibility to be useful in knitting.

GB-A-388 561, GB-A-476 569 and US-A-2,633,421 disclose processing methods in which a fibrous plant is subjected to pressure steam and then allowed to expand at atmospheric pressure and subsequently washing is carried out. However, it is a high-pressure treatment aimed at decorticating fiber plants in the form of straw, leaves, grass, ie to separate the bark or woody part from the fibers themselves. The pressures used are in the range of 3.8 to 6.2 MPa.

It is also known to process a spawning linen of the abovementioned type from EP 0 253 825, in which the steam is subjected to a pressure of the order of 3 MPa for a period of the order of 10 seconds or a pressure of about 1.5 MPa for about 90 seconds. seconds, however, after the fibers have been subjected to a pretreatment consisting of impregnation with a basic or acidic solution. The object pursued according to this specification is to obtain a flax fiber which is substantially free of woody components.

Thus, the object of the invention is quite different, and the pressurized steam conditions are determined precisely so that a smaller amount of organic binder substances persists, yet sufficient to allow a good wet spinning process.

- 1 GB 283915 B6

SUMMARY OF THE INVENTION

To achieve the above object, the invention proposes a method for producing wet flax yarn, wherein the screed fibers are subjected to various preparatory processes to form a fiber strand or yarn, and then the fiber strand or yarn is wet-spun to form a flax yarn whose the principle is that before the preparation processes the fibers obtained from screed are cut to a length in the range from 150 to 400 mm, the cut fibers are soaked with water, the water soaked fibers are exposed to steam in the reactor under a pressure of 1 to 1.5 MPa for from 20 to 60 seconds, after which the reactor discharge port is opened to cause expansion to atmospheric pressure by rapidly shifting the internal pressure of the reactor to atmospheric pressure, after which the treated fibers are washed and dried. Cutting the fibers to a length in the range of 150 to 400 mm allows the preparation of the sliver to be carried out on a preparation device which is not necessarily of the linen type, but can be of the wool or even cotton type.

With the method according to the invention, it becomes thus possible to form a wet-spun linen yarn by means of a preparation circuit which is simpler and less expensive.

The preliminary operations aim to substantially reduce the amount of organic binder materials while maintaining a sufficient amount to allow wet spinning and to maintain the natural appearance of the yarn. In addition, the combination of the aforesaid pressure steam treatment and wet spinning of the yarn provides a very good regularity of the residual binder distribution. It is this regularity and a smaller amount of binders that allow to achieve the desired result, ie increased flexibility while maintaining the traditional appearance and texture.

According to a further feature of the invention, the fiber strand obtained from the preparatory processes is provided in the wet-spinning of an elongation that provides the obtained spun linen yarn with a length of 50 to 140 times the initial length of the strand before wet-spinning. Wet spinning is carried out with this strand-based stretch that has not been subjected to pre-spinning on the flugelhorn. It is thus possible to avoid the first spinning phase, which consists of spinning on a flugelhorn, by simply and simply increasing the spinning delay without compromising the regularity of the yarn obtained.

According to a further feature of the invention, the filaments in the form of tow are cleaned by passage through a carding machine, at the output of which a primary fiber strand is obtained which is cut to form fibers subjected to preparatory processes and wet spinning.

Preferably, after the preparatory processes and before wet spinning, the fiber strand or strand is subjected to an alkaline pretreatment, in particular sodium carbonate solution.

Preferably, after the preparatory processes and before wet spinning, the fiber strand or roving is subjected to bleaching, in particular with oxygenated water.

The invention makes it possible to obtain a flax yarn as described above, characterized in that it has the appearance and structure of a wet-spun yarn and a flexibility sufficient for use in knitting on a knitting machine.

The invention is explained in greater detail in the following by way of example of the production of wet spun linen yarn for use in knitting.

DETAILED DESCRIPTION OF THE INVENTION

The starting material is made from rubbing tow coming from the scouring of the unborn flax. For example, flax was harvested prematurely in the case of dew in the field. Compared to flax normally dewed, the undergrowth of flax contains more and more woody substances, to the extent that the binder which binds the fibers between them could not be sufficiently decomposed by the bacteriological action of the dew.

- 7 GB 283915 B6

The tow is subjected to pre-treatment by cleaning the rental card, from which it exits in the form of a strand. The strand is cut into sections with a length of 300 mm. The material thus cut is introduced into a reaction vessel, where it is impregnated with pure water, then subjected to hydrolysis in water vapor at a pressure of 1.5 MPa for 40 seconds. After this time, opening the outlet port of the reaction vessel causes a rapid opening by passing a pressure of 1.5 MPa to atmospheric pressure and thus expelling the flax through the port to a container containing lightly alkaline water where it is washed and then rinsed.

After drying, the fibers of the treated flax are transformed into a sliver of 4 g / m by passing through a preparation machine by successively passing through a fine carding machine, passing through the GN4 Spinning and Drying Machine, two passes through the combing machine. GN5 without passing flugelhorn.

At the end of the preparation, the strand fineness is characterized by an IFS of 16.74 and a CV% of 5.07. It should be noted that for flax not treated in this manner, the IFS value is greater than 29, which is a good indication of the fiber fineness increment of the present invention.

The strand is subjected to a slight removal of sticky components with a solution of 2.5 g / l of sodium carbonate.

Wet spinning is carried out on a spinning machine with two bands. The pressure of the stretch rollers is obtained by means of a counterweight system. The strand passes into a container filled with cold water and is guided both at the inlet and at the outlet of the draft system by ceramic guides.

In a specific but non-limiting example embodiment, the spacing of the stretch rollers is 80 mm for the rear zone and 60 mm for the front zone. The twist is 410 z / m and the receiving speed is approximately 13 m / mm. The flax yarn obtained has a metric number of 23, a strength of Pkm 17 (CV% 20 to 25) and an elongation of 1.6 to 1.8%.

This yarn, whose appearance and structure corresponds to traditional wet-spun linen, is characterized by a comparatively high flexibility, making it suitable for use in conditions acceptable to work on knitting machines, in particular circular knitting machines, and hence suitable for use in knitting.

The invention is not limited to the described embodiment, which serves only as a non-limiting example. In particular, the length of the shearing may be determined by one skilled in the art depending on the preparation circuit to be used, i.e. the device primarily intended for flax, wool or cotton. In addition, the strand may be subjected to various treatments such as bleaching prior to wet spinning, resulting in the manufacture of bleached flax yarn.

Claims (5)

PATENT CLAIMS A method for producing a wet linen yarn, in which the fibers which have been wiped are subjected to various preparatory processes for forming a fiber sliver or yarn, after which the fiber sliver or yarn is wet-spun to form a linen yarn, characterized in that before the The scrubbing processes are cut to a length in the range of 150 to 400 mm, the cut fibers are soaked in water, the water soaked fibers are subjected to steam in the reactor under a pressure of 1 to 1.5 MPa for 20 to 60 seconds, after which the outlet of the reactor is opened to cause expansion to atmospheric pressure by rapidly shifting the internal pressure of the reactor to atmospheric pressure, after which the treated fibers are washed and dried. -3 CZ 283915 B6 Method according to claim 1, characterized in that the fiber strand obtained from the preparatory processes is provided in the wet-spinning process to give the obtained spun linen yarn a length of 50 to 140 times the initial length of the strand before wet-spinning. Method according to claim 1 or 2, characterized in that the filaments in the form of tow 5 are cleaned before being cut by passing through a carding machine, at the output of which a primary strand of fibers is cut to form fibers subjected to preparatory processes and wet spinning. . Method according to claim 1, characterized in that after the preparation processes and before the wet spinning, the fiber strand is subjected to an alkaline pretreatment, in particular with a sodium carbonate solution. Method according to claim 1, characterized in that after the preparation processes and before the wet spinning, the fiber sliver or yarn is subjected to bleaching, in particular with oxygenated water.